1. Field of the Invention
The invention relates generally to a reduced friction coupling which assists in connecting and disconnecting of two members of a supporting apparatus and, more specifically, to a reduced friction coupling device which interconnects a lower, supporting member and an upper, supported member of a concrete forming apparatus to permit quick and easy disassembly of the supporting member even under load from a formed concrete structure.
2. Background of the Prior Art
Concrete forming apparatus is in wide use in the construction of buildings, bridges, and other concrete structures. The formwork against which the concrete is formed is often held in place by shoring apparatus. In forming horizontal concrete building sections, such as floors and the like, the substantially horizontally disposed formwork is supported on a plurality of vertical support members which are capable of withstanding the applied load of uncured concrete poured upon the formwork. Once the poured concrete has set to a sufficient degree, the formwork is stripped from the concrete structure. Whether the concrete structure is substantially vertical or horizontal, or virtually any other orientation, it is frequently found that a substantial force is exerted by the formed concrete structure against the formwork and hence the structural members which support the formwork. By way of example, if the poured concrete structure is a horizontally disposed floor or ceiling, a significant proportion of the weight of the concrete structure will bear against the formwork and hence against the support members. Accordingly, in order to strip the formwork away from the poured concrete structure, it is necessary to reduce the vertical extension of the support members so as to be able to lower the formwork.
Commonly, the formwork is commonly supported by a lower support member made of steel which supports an upper, supported member, often made of aluminum, which is interconnected to the supporting member by a cast steel wing nut threaded on the supporting member. A pair of steel washers are interposed between the wing nut and the supported member. The wing nut is rotated relative to threads in the supporting member to move the supporting and supported member relative to each other so as to reduce the vertical height of the support member and move the formwork away from the poured concrete structure. The load on the support member by the poured concrete structure, however, makes it extremely difficult to loosen the wing nut. It is common for workers to overcome this resistance by extending the lever arm for moving the wing nut by using a section of pipe connected to the wing nut and then either hammering on the pipe in order to forcibly move the wing nut or, in more difficult circumstances, using a fork lift or other powered device to push against the pipe and thereby forcefully rotate the wing nut to strip the formwork from the formed concrete structure. This way of stripping the formwork has several disadvantages. It is difficult for a single laborer to accomplish, it often requires the use of ancillary equipment, and it requires the exertion of extremely high forces on the support members.
The high force required to release the wing nut is due to several factors. The primary factor was believed to be a result of the high coefficient of friction between the cast wing nut and the threads of the steel supporting member. There is also a high coefficient of friction between the steel washers and the aluminum supported member. Further, it is common for galling of the relatively soft facing surface of the supporting member to occur during tightening and loosening of the wing nut.